All mammals, and in particular humans, can suffer from dryness on particular areas of the body. The skin and mucosal membranes of the body are most often affected. Dryness of the skin or mucosal membranes can be cosmetically unattractive. In addition, the dryness can result in a certain degree of itching and pain. With respect to mucosal membranes, the dryness is the result of the generation of an insufficient quantity of mucoproteins and mucopolysaccharides on the affected area to hold fluid in contact with the cells. When insufficient moisture is present, the mucoproteins and mucopolysaccharides cannot create a sufficient barrier to irritation and infection. Accordingly, the affected individual is subjected to a higher degree of local infections with respect to the affected area, and such local infections can spread systemically. When such a systemic infection results, the consequences can be quite serious. Accordingly, it is important not only to relieve dryness in affected areas, but also to prevent the initial formation of dryness and therefore prevent the initial infections.
In our earlier application titled "Method and Composition for Treating Xerostomia", we discussed compositions and methods of treating that particular type of dryness. Xerostomia is a condition in which the salivary glands do not produce sufficient quantities of saliva. This causes discomfort which can in some cases be quite severe. Without saliva, the mouth burns and the throat and tongue can undergo radical changes. Teeth can decay rapidly and the tongue can become smooth, cracked and vulnerable to infection. There is often a loss of taste and, because saliva contains important digestive enzymes, there are often problems with digestion.
Cases of xerostomia may vary from the mild, in which only slight dryness is experienced, to severe cases in which the patient will have serious problems with mastication, swallowing, digestion, speech, and the like. As noted in U.S. Pat. No. 4,438,100 to Balslev et al., there are a number of causes of xerostomia, including the physiological (e.g., age, menopause, postoperative conditions, dehydration), as well as the psychic (nervousness). The reasons for mouth dryness may also be pharmacological (e.g., as a common side effect of many medications, including diuretics, antiarthritics and antidepressants) or as a result of radiotherapy. In addition to causing dry mouth, these factors can cause dryness of other areas such as vaginal dryness. The most severe cases of xerostomia, as well as other types of dryness are caused by radiation therapy (after head and neck surgery) and by autoimmune diseases such as lupus, Sjogrens Syndrome, and rheumatoid arthritis. See, for example, P. C. Fox et al., J. Am. Dental Assoc. 110:519-525 (1985).
A number of different compositions and methods for treating various types of dryness are described within the literature. For example, U.S. Pat. No. 4,232,003 issued Nov. 4, 1980 to Posthuma et al. discloses a composition referred to as a synthetic physiological mucous which is indicating as having particular usefulness in connection in treating the dryness of vaginal tissues and as a surgical lubricant. The composition is a pituitous aqueous solution of a high molecular polyacrylamide. Such synthetic mucous compositions and methods for using such compositions to treat dryness are also disclosed within U.S. Pat. No. 3,965,906 issued June 29, 1976.
The general concept of imparting lubricicity to a substrate such as skin, hair or mucous membranes is discussed within U.S. Pat. No. 4,128,631 issued Dec. 5, 1978. The inventors disclosed the use of a composition which includes a high molecular weight salt having a particular structural formula and molecular weight range.
A more specific type of lubricating composition in the form of a vaginal suppository is disclosed within U.S. Pat. No. 4,347,237 issued Aug. 31, 1982. The suppository is solid at room temperature and melts at body temperature due to its composition which includes a variety of different types of water soluble polyoxy alkylene polyol components.
As indicated above, the literature includes a number of disclosures of compositions and methods of applying those compositions to a substrate such as skin or mucous membranes in order to improve lubrication or relieve dryness. The effect is generally obtained by the application of a synthetic lubricant or a synthetic moisturizer and not by the inclusion of an active ingredient within the composition. However, U.S. Pat. No. 4,184,974 issued Jan. 22, 1980 to Leuven discloses a lubricant composition which includes a topical biocidal agent. A similar type of composition containing such a biocidal agent is disclosed within U.S. Pat. No. 4,267,168 issued May 12, 1981.
The present invention is premised on the surprising discovery that the oil extracted from the Yerba Santa plant (Eriodictyon californicum; Eriodictyon qlutinosum; also known as "consumptive's weed"; "bear's weed" "mountain balm" and "gum plant") is extremely effective in providing long-lasting relief of a variety of types of mild to severe dryness of dermal and mucosal membranes, with no unpleasant side effects.
The Yerba Santa plant is an evergreen shrub indigenous to the hills and mountains of California and northern Mexico, and was long used by Indians for a number of purposes. See, e.g., A. R. Hutchens, Indian Herbalogy of North America, Ontario: Merco, 1975, at pp. 317-318. A number of references to the Yerba Santa plant teach its use as an expectorant (e.g., N. Coon, The Dictionary of Useful Plants, Emmaus, Pa.: Rodale Press, (1974)), in treating colds, sore throats, catarrh, stomach aches, vomiting and diarrhea (see A. R. Hutchens, supra), in treating hemorrhoids (D. G. Spoerke, Herbal Medications, Santa Barbara, Cal.: Woodbridge Press, 1980, at p. 183), in treating diseases of the lung (Los Remedios de la Gente: A Compilation of Traditional New Mexican Herbal Medicines and Their Use, compiled by M. Moore, 1977), and in masking the taste of quinine and other bitter medications (Spoerke, supra; see also G. E. Trease et al., Pharmacognosy, London: Cassell & Colber, 1978, at p. 463)).
Publications discussing the Yerba Santa plant include the Coon, Hutchens, Moore, Spoerke, and Trease et al. references, cited in the preceding section, as well as V. J. Vogel, American Indian Medicine, The University of Oklahoma Press, 1970, at pp. 83, 399-400; W. H. Lewis et al., Medical Botany: Plants Affecting Man's Health, New York: John Wiley & Sons, 1977, at p. 301; P. Huson, Mastering Herbalism: A Practical Guide, New York: Stein and Day, 1974, at p. 32; B. C. Harris, The Compleat Herbal, Barre, Mass.: Barre Publishers, 1972, at p. 197; N. Coon, Using Plants for Healing, Hearthside Press, 1963, at p. 122; M. Grieve, A Modern Herbal, vol. 22, New York: Hafner Publishing Co., 1959, at p. 865; and V. E. Tyler et al., Pharmacognosy, Philadelphia: Lee & Febiger, 1981, at p. 148.